Improves gevent recipe robustness

Tries to match and replace patterns to be moved from one environment
variable to another rather than hard coding it.
That way unexpected flags added to parent recipes hierarchy also get
handled.
This issue popped when testing #793

Author: AndreMiras

pythonforandroid/recipes/gevent/__init__.py

@@ -1,4 +1,5 @@
-import os
+import re
+from pythonforandroid.logger import info
 from pythonforandroid.recipe import CompiledComponentsPythonRecipe
 
 
@@ -9,19 +10,24 @@ class GeventRecipe(CompiledComponentsPythonRecipe):
     patches = ["gevent.patch"]
 
     def get_recipe_env(self, arch=None, with_flags_in_cc=True):
+        """
+        - Makes sure the linker is the cross compiler one.
+        - Moves all -I<inc> -D<macro> from CFLAGS to CPPFLAGS environment.
+        - Moves all -l<lib> from LDFLAGS to LIBS environment.
+        """
         env = super(GeventRecipe, self).get_recipe_env(arch, with_flags_in_cc)
         # sets linker to use the correct gcc (cross compiler)
         env['LDSHARED'] = env['CC'] + ' -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions'
         # CFLAGS may only be used to specify C compiler flags, for macro definitions use CPPFLAGS
-        env['CPPFLAGS'] = env['CFLAGS'] + ' -I{}/sources/python/3.5/include/python/'.format(self.ctx.ndk_dir)
-        env['CFLAGS'] = ''
+        regex = re.compile('\s*-[DI][\S]+')
+        env['CPPFLAGS'] = ''.join(re.findall(regex, env['CFLAGS'])).strip()
+        env['CFLAGS'] = re.sub(regex, '', env['CFLAGS'])
+        info('Moved "{}" from CFLAGS to CPPFLAGS.'.format(env['CPPFLAGS']))
         # LDFLAGS may only be used to specify linker flags, for libraries use LIBS
-        env['LDFLAGS'] = env['LDFLAGS'].replace('-lm', '').replace('-lcrystax', '')
-        env['LDFLAGS'] += ' -L{}'.format(os.path.join(self.ctx.bootstrap.build_dir, 'libs', arch.arch))
-        env['LIBS'] = ' -lm'
-        if self.ctx.ndk == 'crystax':
-            env['LIBS'] += ' -lcrystax -lpython{}m'.format(self.ctx.python_recipe.version[0:3])
-        env['LDSHARED'] += env['LIBS']
+        regex = re.compile('\s*-l[\w\.]+')
+        env['LIBS'] = ''.join(re.findall(regex, env['LDFLAGS'])).strip()
+        env['LDFLAGS'] = re.sub(regex, '', env['LDFLAGS'])
+        info('Moved "{}" from LDFLAGS to LIBS.'.format(env['LIBS']))
         return env